Six Afghan police officers and two U.S. soldiers have been killed in separate roadside bombings in southern Afghanistan.

Afghan officials say the police officers were killed and four others wounded Monday when a bomb ripped through their vehicle in the Khakrez district of Kandahar province. The Taliban claimed responsibility for the attack.

Two American soldiers were killed in separate bomb attacks in the south Monday. NATO did not give details.

Militants have stepped up attacks as U.S.-led NATO and Afghan forces work to clear Kandahar and surrounding areas of Taliban insurgents.

The latest violence comes as the Afghan government prepares to host a major international conference on Afghanistan in Kabul Tuesday.